Oral Cavity, Oral Pharynx and Palatine Tonsil

Palpable structures in the vestibule of the oral cavity

The vestibule of the mouth is the space between the lips and the teeth.
If you start in the mid line along the bottom, you can feel the inferior
frenulum. Move your finger to the side until it moves up along a ridge,
this is the anterior border of the ramus of the mandible. While your finger
is on this border, bite down and you will feel the masseter muscle contracting.
If you move your finger as far up as you can go, you will feel the coronoid
process of the ramus and the tendinous insertion of the temporalis muscle.
Now move your finger in the upper recess of the vestibule until you come
to the mid line again and you will feel the upper frenulum. Look in your
own mouth for the opening of the parotid duct that enters the vestibule
opposite the 2nd upper molar tooth.

Oral Cavity Proper

Structures that you should be able to feel or see in your own mouth.

Figure 1.

First, the boundaries of the mouth are:

superior--hard and soft palates

inferior--tongue and floor of mouth

anterolateral--upper and lower teeth

posterior--palatoglossal fold (5)

Structures to identify:

vestibule

hard palate

soft palate

uvula

palatoglossal arch

palatine tonsil

palatopharyngeal arch

posterior wall of oropharynx

pterygoid hamulus

Figure 2. Tongue elevated.

frenulum of tongue

ridge formed by deep lingual vein

sublingual fold

sublingual caruncle

opening of submandibular duct

The sublingual gland forms the sublingual fold and sends multiple small
ducts into the mouth along the fold.

Figure 1

Figure 2

Surface of the tongue viewed from above.
Note the tip of tongue, epiglottis and soft palate with the uvula as
points of reference!

Identify:

anterior 2/3rd of tongue

posterior 1/3rd of tongue

palatogossal fold

palatine tonsil

fungiform papillae

circumvallate papillae

sulcus terminalis

foramen cecum

foliate papillae

Innervation:
Anterior 2/3rd:

general sensation--lingual nerve (V3)

taste--chorda tympani (VII)

Posterior 1/3rd:

general sensation--glossopharyngeal (IX)

taste--glossopharyngeal (IX)

Floor of the Mouth

Here is a perfect example of how important it is to orient yourself.
In order to show the structures in the floor of the mouth, the tongue must
be reflected posteriorly (notice the vertebral column). I always look for
the
mandible for anterior orientation.
In opening up the floor of the mouth, the mucous
membrane is gently incised just above the sublingual gland and the fascia
covering the gland (sg) is pulled posteriorly along with the tongue. This
reveals:

mylohyoid muscle (floor)

geniohyoid muscle just above the mylohyoid

The mylohyoid muscles of the two sides joint in the mid line forming a
sling across the floor of the mouth. In the section of the head and neck,
the mylohyoid muscle can be seen in cross section.

Note where the tip of the tongue isIt has been displaced posteriorly.

Removal of the fascia around the sublingual gland (slg) and the deep
part of the submandibular gland (sm) allows you to visualize the remainder
of the structures of the mouth.

styloglossus muscle (sg)

hyoglossus muscle (hg)

genioglossus muscle (gg)

submandibular duct (5)

lingual nerve (1)

submandibular ganglion (2)

hypoglossal nerve (3)

C1 nerve to geniohyoid (4)

You can also see the genioglossus muscle from the sectioned tongue.

Muscle

Origin

Insertion

Action

Nerve Supply

styloglossus

styloid process

merges with hyoglossus and genioglossus muscles in the tongue

draws tongue up and back to aid swallowing food

XII

hyoglossus

greater horn of hyoid bone

merges with styloglossus and genioglossus muscles

draws side of tongue down

XII

genioglossus

genial tubercle of mandible

fans out in the tongue to make up the bulk of the tongue

pulls tongue forward, sticking the tongue out

XII

intrinsic muscles

tissues of tongue

tissues of tongue

produce small changes in the contour of the surface of tongue

XII

mylohyoid

mylohyoid line of mandible

hyoid bone and raphe

elevates hyoid bone and floor of mouth to aid in swallowing

nerve to mylohyoid (V3)

geniohyoid

lower genial tubercle of mandible

body of hyoid bone

elevate hyoid bone or depress mandible

C1

You will now identify the structures found in the lateral wall of the
oropharynx. This is where the palatine tonsil is located. Again, orient
yourself: identify the tongue, hard palate, hyoid bone and soft palate.
Identify the palatoglossal arch and the palatopharyngeal arch. Find
the palatine tonsil between the two arches, if it is present. Beneath the
mucosa of the arches, identify the small palatoglossus (pg) and palatopharyngeus
(pp) muscles. You might also see the superior pharyngeal constrictor (SC)
and middle pharyngeal constrictor (mc) at this stage.

When the tonsil is removed, you can see the structures that make up
the tonsillar bed and that could be injured during a tonsilectomy.

superior pharyngeal constrictor (SC)

pterygomandibular raphe (PR)

middle pharyngeal constrictor (MC)

tonsillar branch of facial artery (1)

glossopharyngeal nerve (2)

stylohyoid ligament (3)

You might also be able to see the buccinator muscle (BUC) in this dissection.
The pterygomandibular raphe serves as an insertion point for two muscles:
superior constrictor and buccinator.